Multifunctional non-Hermitian metasurface: metalens and holograms.

Exceptional points (EPs) have been the subject of wide concern because of their unique physical properties and have produced many related applications. However, up to now, most non-Hermitian metasurfaces related to EPs focus on realizing a single function. It remains a challenge to integrate multiple functions into a single non-Hermitian metasurface while making it dynamically adjustable. In this work, we investigated how to combine the Pancharatnam-Berry (PB) phase and exceptional topological (ET) phase and used the polarization decoupling property of EPs to design and realize the integration of multiple functions on a metasurface with the assistance of vanadium dioxide (VO₂). As an example in applications, the phase-only metalens and dual-channel holograms can be realized and switched by changing states of the VO₂ and incident light polarization. This work will open a prospect for researching a multifunctional non-Hermitian metasurface and the design of switchable multifunctional nano-photonic devices.